Tepco Says Contaminated Water Tank Leak May Have Started in July

Aug. 28 (Bloomberg) -- The leak at a contaminated water
storage tank discovered last week at the Fukushima plant may
have continued since last month before it was detected and the
tank drained, plant operator Tokyo Electric Power Co. said.

Crews found elevated levels of radiation in July near where
the leak was ultimately detected on Aug. 19, Mayumi Yoshida, a
spokeswoman for the utility known as Tepco, said today by phone.

Tepco originally characterized the leak as a small one
before determining by the change in the tank’s water level that
300 metric tons of contaminated water had escaped. A protective
barrier around the tank didn’t stop the leak because a valve in
the concrete structure had been left open, Tepco said.

Japan’s Nuclear Regulation Authority last week labeled the
leak a “serious incident” in its worst assessment of the
problems at Fukushima since the earthquake and tsunami of 2011
caused reactors to melt down.